Tricia Thompson, MS, RD

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Manufacturers of Gluten-Free Food: Are They Testing for Gluten?

If you think a gluten-free label means that a food has been tested appropriately for gluten think again…

Suzanne Simpson, dietitian at the Celiac Disease Center at Columbia University has been contacting manufacturers with one simple question, “Do you test your products for gluten content using the Standard R5 ELISA Ridascreen 7001?”

Suzanne agreed to share what she learned, some of which may surprise you.

Tricia’s Note: The test Suzanne asked manufacturers if they were using—the R5 ELISA (R7001 Ridascreen Gliadin)–is widely regarded as the best available validated ELISA for assessing final food products for gluten. The R5 ELISA is one of only two commercially available ELISAs validated at the levels used for regulatory purposes and official governmental methods (the other is the Morinaga Wheat Protein ELISA). The R5 ELISA is included in the FDA’s proposed gluten-free labeling rule as a possible method for rule enforcement.

What was your motivation for contacting manufacturers of labeled gluten-free foods regarding their testing protocols? I am consulted regularly to see patients with celiac disease that have persistently elevated celiac antibodies despite adhering to a gluten-free diet for longer than 1 year. For some patients, I am able to find hidden gluten sources in restaurant food (such as deep fried Mexican corn chips or French fries cooked in a non-dedicated fryer) but for some patients I am unable to determine the source of their gluten exposure. Because gluten exposure is the main reason for persistently elevated celiac antibodies I started to investigate the foods that were regularly being consumed to make sure they were really safe on the gluten-free diet. I started to contact manufacturers to ascertain whether testing was a regular part of the various companies’ protocol.

Approximately how many companies did you contact? I rarely contacted companies that have already been certified by the GIG or CSA. I also did not contact companies that have allergen information on their website, such as Kellogg’s or Kraft. I did contact approximately 78 companies.

How many of the 78 companies responded? Of the 78 companies contacted, 66 (85%) of them either responded or had their testing procedures on their website.

Of those who responded how many are testing their finished food products for gluten? Out of the 66 companies that did respond, 58 (88%) of them are testing.

Only 4 companies specifically said they use the R5 ELISA. The majority did not know which test was being used other than that it was an ELISA.

Tricia’s Note: The two ELISAs generally used in the US are the sandwich R5 ELISA and the sandwich omega-gliadin (Skerritt) ELISA. The omega-gliadin ELISA is no longer considered state-of-the-art. One of its drawbacks is that it severely underestimates contamination from barley having a cross-reactivity of only 4 to 8%

What other tests are manufacturers using? Some companies are using the Lateral Flow, Fast Gliadin, EZ Gluten, or the EZ Rapid Gliadin.

Tricia’s Note: The EZ Gluten test utilizes the omega-gliadin antibody. The Ridascreen Fast Gliadin utilizes the R5 antibody. The intended use for the Ridaquick Gliadin Lateral Flow test is to qualitatively (but not quantitatively) test for gluten.

What reasons did manufacturers give for not testing product? “We are a dedicated gluten-free facility.”

Tricia’s Note: Using a dedicated facility is NOT a legitimate reason for not testing food products for gluten. Grains, flours, and other ingredients can arrive at a dedicated gluten-free manufacturing facility already contaminated with gluten. Remember, contamination can occur in the field, during transport, and at the grain/flour processing plant. Unless every single supplier is frequently testing at-risk ingredients for gluten using the standard sandwich R5 ELISA, gluten-free manufacturers must test their final food products for gluten contamination. Not to do so is irresponsible at the very least.

What did you learn about manufacturers and testing that surprised you the most? What surprised me was the lack of knowledge about which tests are most appropriate for accurate information about gluten content.

What advice are you giving your clients regarding the labeled gluten-free foods they eat? I tell all celiac disease patients to buy grains, flours, cereals, breads, baked goods, cookies, pastas etc. that have a gluten-free claim. I also advise that processed meats/ poultry should be labeled GF. I teach them about which ingredients are safe in both FDA and USDA regulated foods. For clients that have persistently elevated celiac antibodies I advise them to look for the certification stamps and to buy brands that are being tested for gluten content.

Thank you Suzanne!

Just a reminder that I have started a new website (www.glutenfreewatchdog.org) for the unbiased reporting of gluten-free food testing data for consumers. The site is available for preview and two products reports (i.e., Bob’s Red Mill Whole Grain Brown Rice Flour and Betty Crocker’s Gluten-Free Yellow Cake Mix) are available for review. Please visit and let me know your thoughts. Thanks!